High capacity, high speed, and low power memory is in demand for many different high powered computing systems, such as servers, entertainment distribution head ends for music and video distribution and broadcast, and super computers for scientific, prediction, and modeling systems. The leading approach to provide this memory is to mount a large number of spinning disk hard drives in a rack mounted chassis. The chassis has a backplane to connect to each hard drive and to connect the hard drives to other rack mounted chassis for computation or communication. The hard disk drives connect using SAS (Serial Attached SCSI (Small Computer System Interface)), SATA (Serial Advanced Technology Attachment), or PCIe (Peripheral Component Interface express) or other storage interfaces.
Flash arrays are constructed at high volume in a 2.5″ hard disk drive form factor and in a M.2 module form factor. These form factors have been specifically developed for notebook computers and provide an amount of storage, speed, power consumption and cost that is best suited for notebook computers. An AFA (All Flash Array) could be built using these standard form factor SSDs (Solid State Drives). When off the shelf 2.5″ SSDs are used for a large capacity solution and they are vertically mounted there is a minimum rack-mount chassis size of 2 U or 3 U due to the size of the drives, the mounting connectors and the need for airflow. M.2 SSDs have a lower capacity and so require many more devices and connectors.
In high speed memory arrays, the fans and the memory storage are most prone to failure. The fans are in constant use and the mechanical bearings and motors wear over time. The memory storage is in constant use and is stressed by high speed applications. Each memory cell has a limited number of read and write cycles in its lifetime and the other components of a memory may also wear or fail from temperature and usage stress.
To service a flash array, the chassis slides forward out of the rack partly or fully and a lid is removed to provide access to the memory cards or SSDs. A special cable solution is provided to allow the chassis to move forward without being disconnected at the rear. In some cases front mounted 2.5″ SSDs are used to allow the drives to be serviced without moving the chassis. The front serviceable SSDs require middle mounted fans to allow access to the SSDs from the front.